Invisible Tanks by 2012?

[Letum]

Originally Posted by P_Funk

Well if you take into consideration the speeds which the projectile is going to reach as it runs along the rails and then the subsequent friction caused you can imagine that finding a metal that is highly conducting but also heat and wear resistant can be tough.

Originally Posted by baggygreen

As i understood it, there was no recoil, but the problem lay with the energy source as you mentioned. Id not heard of rails wearing out, tho i suppose it is logical..

It's not the friction thats the problem, its the high voltage that runs through the projectile.

The electricity runs up one rail, through the projectile and down the other rail. If there is
any tiny amount of resistance between the projectile and the rail then you will get
ultra hot sparks and metal welding.

In short:
Electrical resistance causes heat. Heat causes metallic melting.
There is always lots of electrical resistance between the rails and the projectile.
The rails and projectile will melt and weld.

To fix this you can either:
1) try to drop the temperature of the rails to just a few kelvin.
This requires a large setup and is not efficient. It also limits the power you can use.
It is never 100% effective.

2) try to reduce resistance between the rail and projectile.
there are many ways to do this, but they all increase kinetic friction.
It is never 100% effective.

The only alternative is a "one shot" weapon.

Regarding recoil:
There is plenty of recoil, but this isn't a big problem as long as the gun is fixed to the
ground or a large ship. It might be a problem with metal fatigue on smaller railguns.

Regarding friction:
It is theoretically possible to make a rail gun with zero friction because the projectile
does not need to touch the rails, so this isn't a problem.


Regarding energy source:
Again, not a big problem. As long as you have enough time than you can get as
much energy as you want into a bank of compasstours.


Whats so good about rail guns?
If you can make a rail gun that wont weld it's projectile to the rails, then a 1lb non-explosive
projectile could impact with enough speed to cause highly explosive force equivalent to
several tonnes of conventional explosive.
Range is limited by the curve of the earth.


What isn't so good about rail guns?
They are very big, immobile, hard to target over range, can only be used a few times
and they are somewhat unproven.